I've got a couple of AR applications and an inventory application. I do not try to store balance, past due, quantity on hand, etc. I calculate them on the fly. Aged receivables (30-60-90 days), account balances, etc can all be calculated from transactions. In your case, if they call asking for balances all the time I'd create a query that calculated the balance by customer, and base a form or report on it. You can restrict it to the one customer that's calling with the wherecondition argument of OpenForm.